Drawing instrument.



.m\ .JINN NN.. I l /V PATENTED PEB. 7, 1905. J. HOFFMANN.

DRAWING INSTRUMENT.

APPLICATION FILED MAB. 14. 1904.

. fill Patented February '7, 1905.

UNITED STATES ATENT OFFICE.

JOBST HOFFMANN, OF NElV YORK, N. Y.

DRAWlNG INSTRUMENT.

SPECFICATION forming part of Letters Patent No. 781,724, dated February 7, 1905.

Application filed March 14,1904. Serial No. 198,173.

To ftZZ whom it may concer/L:

Be it known that vI, Jons'r HOFFMANN, a citizen ot' the United States, and a resident of the city of New York, borough ot' Manhattan, in the county and State ot' New York, have invented a new and Improved Drawing' VInstrument, otl which the lt'ollowing is a full, clear, and exact description.

This` invention relates particularly to improvements in T-squares or right-line rules, an object being' to provide a device ot' this character so constructed that it may be slid overa drawing without dang'er ot' blurring ink-lines that Inay not be dry, thus resulting in a saving' of time in making' drawing's.

Other objects of 4the invention will appear in the general description.

l will describe a drawinginstrument embodying' my invention and then point out the novel 'features in the appended claims.

Reference is to be had to the accompanying' drawings, forming a part of this specification, in which similar characters of reference indicate corresponding' parts in all the figures.

Fig'ure 1 is a top plan View ot' a drawing instrument embodying my invention. Fig. 2 is a bottom plan View thereof. Fig'. 3 is an edge view. Fig'. a is a detail plan showing' a means for adjusting' the ang'le ot the instrument. Fig. 5 is a section on the line 5 ot' Fig. 1. Fig. 6 is a sectionon the line 6 6 ot Fig'. 1, and Fig'. 7 is a section on the line T T of Fig. 1.

Referring' to the drawings, 10 designates a rule, on one end ot' which is secured a crosshead 11. These parts may consist otl any suitable material-such for instance, as wood or metal-and for the sake of lightness, with necessary streng'th, the rule 10 is cored out or recessed at the under side, as .indicated at 12, and arched at the top. it the center, however, there is a longitudinal rib 13, in which is seated a metal plate 14:, which will prevent any lateral springing' otl the rule.

At the ends otl the rule and on the under side thereot` are blocks 15 16, which are designed to bear upon the drawing-board 17 and to raise the intermediate or body portion of the rule above the drawing' that may be on l i l l l i l j the board, rthus permitting the rule to be moved over the drawing without danger otl blotting' or blurring' wet lines. lVhen the device is used on short boards, I may employ supplemental blocks or plates 17, which are removably secm'ed to the rule, and in instances where the paper or tracing-cloth Inay be somewhat loose on Ithe board l may employ an extending' plate 18, consisting ot' metal or the like. This plate 18 has pins 19 designed to engage in pert'orations formed in the rule, and it may be adjusted by means ot' a screw 21), passing' through the rule and engaging in a threaded sleeve 21, attached to the plate.

It sometimes happens that a pencil-drawing is transferred from one board to another for inking, and as the boards or T-squares may not to be of the same character or slightly out of relation with each other 1 provide a means whereby the present instrument may be adjusted to the differences in line angles. This means consists of spring-plates 22, attached to the head 11 and regulated by means of screws 23, arranged in the head and manipulated by linger-pieces 21,cwhich project through slots formed in the head.

Removably attached to the rule 10 are scaleplates By making' the plates removable it is obvious that any required scales may be used in connection with the rule.

Having thus described my invention, [claim as new and desire to secure by Letters Patent 1. A drawing' instrument com prising a rule arched at the top and recessed at the under side, a longitudinal rib in said recess, a stitlening-plate arranged in said rib, blocks on the under side and at the ends ot' the rule whereby the intermediate portion is elevated, and a cross-head on the rule.

2. A drawing instrument comprising' a rule, arched at the top and recessed at the under side, a longitudinal rib on the under side otthe rule, a metal plate in said rib, and blocks on the under side of the rule tor elevating' the same.

3. A drawing' instrument comprisinga rule, an elevating-block consisting' ot' a plate, pins rule, and an adjusting-screw for the plate.

In testimony whereof I have signed my name to this speoiiieation in the presence of two sub- I0 scrihing Witnesses.

J OBST HOFFMANN.

/Vitnesses:

J No. M. RITTER, C. R. FERGUSON. 

